he12.asm

51系列单片机的汇编程序包

;===================硬件实验十二  通用打印机===============
        ORG 0240H
        MOV DPTR,#PRTSTR
        MOV R1,DPH
        MOV R0,DPL
        MOV R2,#0FBH            ;R2,R3=长度
        MOV R3,#00H
DOE0:   MOV DPTR,#0FFDBH
        MOV A,#88H
        MOVX @DPTR,A            ;8255控制命令送入
        MOV DPTR,#0FFDBH
        MOV A,#01H              ;关打印机
        MOVX @DPTR,A
DOE1:   MOV DPTR,#0FFDAH
        MOVX A,@DPTR
        JB ACC.4,DOE1           ;打印机忙吗?
        MOV DPL,R0
        MOV DPH,R1
        CLR A
        MOVC A,@A+DPTR          ;取数
        INC DPTR
        MOV R0,DPL
        MOV R1,DPH              ;DPTR加1
        MOV DPTR,#0FFD8H
        MOVX @DPTR,A            ;送打印机
        MOV DPTR,#0FFDBH
        MOV A,#00H
        MOVX @DPTR,A
        NOP
        NOP
        NOP
        MOV A,#01H
        MOVX @DPTR,A            ;开始打印
        DJNZ R2,DOE1
        MOV A,R3                ;NEW ADD
        ADD A,#01H              ;NEW ADD
        MOV R3,A                ;NEW ADD
        DJNZ R3,DOE1            ;若字节未打印完则继续循环
        MOV A,#0DH
        MOV DPTR,#0FFD8H
        MOVX @DPTR,A
        SJMP $
;-------------------------------------------------------------------------------
PRTSTR: DB 0DH,0AH
        DB "=========================================",0DH,0AH
        DB "Welcome use Dais(R) Teaching Apparatuses!",0DH,0AH
        DB "-----------------------------------------",0DH,0AH
        DB "Copyright 2003 (c) Dais Computer Co.,Ltd.",0DH,0AH
        DB "        http://www.qddais.com.cn",0DH,0AH
        DB "-----------------------------------------",0DH,0AH
;-------------------------------------------------------------------------------
        END